More than a billion trees planted in 2007

The United Nations’ Billion Tree campaign met its goal in 2007, the U.N. announced. Ethiopia and Mexico were leaders in the campaign to plant more than 1 billion trees this year, according to a U.N. report.

The mass tree planting was inspired by Nobel Peace laureate Wangari Maathai. The effort was spurred by a desire to mitigate effects of pollution and environmental deterioration.

-- Sarah